Sen. Bernie Sanders’s presidential campaign is the first such effort by a democratic socialist since Norman Thomas waged the last of his six such campaigns on the Socialist Party ticket in 1948.

It’s about time.

Historically, the role of the two great American socialist standard-bearers Eugene Debs and Thomas, and such socialist members of Congress as Meyer London and Ronald Dellums, was to advance ideas that their progressive compatriots were sometimes able to enact — partially — years or decades later, or that later were transformed into common sense. Running for president in 1904, Debs campaigned for the eight-hour workday, social insurance and women’s suffrage. Representing New York’s Lower East Side in Congress during the 1910s, London introduced legislation to create paid maternity leave, something Congress still has yet to get around to. In 1942, Thomas was virtually the only prominent American to publicly oppose the internment of Japanese Americans.

What distinguished the socialists from their contemporaries during the Progressive era and the New Deal was their belief that capitalism was inherently unjust and unsustainable. But the very reforms pushed through by European socialists and their American socialist, progressive and liberal counterparts created a more social capitalism — a capitalism with unions, social insurance and prohibitions on speculation — that was to prove remarkably sustainable for a time. In the years after World War II, the socialist parties of Europe and American socialist intellectuals such as Michael Harrington no longer advocated nationalizing the means of production. They advocated, rather, for an expanded social rights agenda — free medical care, for instance — and civil rights. A. Philip Randolph, Bayard Rustin and Martin Luther King Jr. — respectively, the architect, the organizer and the visionary of the 1963 March on Washington — were democratic socialists.

But the more egalitarian U.S. economy of the postwar decades has given way to a far grimmer one today, in which new jobs pay poverty wages and and just two art auctions at Christie’s this week can entice the rich to part with more than $1.3 billion. Debs would find much of today’s United States disorientingly familiar. Young Americans, who may have heard their nation once had a middle-class majority but have never experienced it themselves, may have no clear idea what socialism is, but they have a grimly accurate read on contemporary capitalism. A Pew poll showed that while 46 percent of 18- to 29-year-olds had a positive view of capitalism, 47 percent had a negative view — and when asked about socialism, 49 percent saw it positively and 43 percent negatively.

Sen. Bernie Sanders (I-Vt.), a White House contender in 2016, is known for his stances on budget issues and war. Here's the Vermont senator's take on Obamacare, Social Security and more, in his own words. (Julie Percha/The Washington Post)

Enter, stage left, Sen. Sanders. The independent from Vermont is not likely, putting it mildly, to displace Hillary Clinton as the Democratic front-runner, or Sen. Elizabeth Warren (D-Mass.) as the leader of U.S. liberalism, but in the best tradition of Debs and Thomas, he is advancing ideas that Democrats, Clinton included, may in time embrace. Sanders calls for Medicare for all and free higher education to be financed with higher taxes on the rich. Like Debs and Thomas, who won their highest votes in elections in which the tide was running left (for Debs, 1912, in which the victor was Woodrow Wilson; for Thomas, 1932, in which the victor was Franklin D. Roosevelt), Sanders is running while Democrats are again moving left in response to the deep dysfunctions of U.S. capitalism. In the past few weeks, leading Democratic think tanks have proposed establishing a public option for health care, national funding for state universities and higher Social Security benefits — policies distinctly more progressive than last year’s standard Democratic fare. Democratic city councils are raising the minimum wage and requiring paid sick days. On Tuesday, Senate Democrats brought the free-trade agreement with Pacific Rim nations to a shuddering, if provisional halt, pending the addition of legislation that pays more heed to the concerns of U.S. workers.

Much of what Sanders champions is a slightly more social democratic version of the newly populist liberalism. He can make an even more helpful contribution by offering proposals to change our economic institutions in ways that re-socialize capitalism — rolling back the power that major shareholders wield over corporations, creating labor rights for workers in the gig economy, making businesses more answerable to their workers and consumers.

Combining his avowed socialism with his gruff grandpa manner, Sanders brings to today’s politics an authenticity otherwise in short supply. At best, his role, like that of Debs and Thomas, may prove to be prophetic. “I am not the champion of lost causes,” Thomas insisted, “but the champion of causes not yet won.”

During a news conference on April 30, 2015, Sen. Bernie Sanders (I-Vt.) spoke about his agenda for the U.S. He also answered questions about how he would campaign against Democratic presidential candidate Hillary Clinton. (AP)